The Effects of Established Trees on Woody Regeneration during Secondary Succession in Tropical Dry Forests

Understanding the mechanisms controlling secondary succession in tropical dry forests is important for the conservation and restoration of this highly threatened biome. Canopy‐forming trees in tropical forests strongly influence later stages of succession through their effect on woody plant regeneration. In dry forests, this may be complex given the seasonal interplay of water and light limitations. We reviewed observational and experimental studies to assess (1) the relative importance of positive and negative effects of established trees on regeneration; (2) the mechanisms underlying these effects; and (3) to test the 'stress gradient hypothesis' in successional tropical dry forests. The effects of established trees on seed dispersal, seed survival, and seed germination—either through direct changes to moisture and temperature regimes or mediated by seed dispersers and predators—are mainly positive. The balance between positive and negative effects on seedling establishment is more complex and depends on the season and leaf phenology of both trees and seedlings. Seedling survival is generally enhanced by established trees mitigating dry conditions. Established trees have counteracting effects on water and light availability that influence seedling growth. The probability of a positive effect of established trees on seedling survival decreases with increased rainfall, which supports the stress gradient hypothesis. Priorities for future research are experiments to test for facilitation and competition and their underlying mechanisms, long‐term studies evaluating how these effects change with ontogeny, and studies focusing on the species‐specificity of interactions

Neighbourhood Reading Clubs: Rekindling Reading Interest among Nigerian Children

A common comment on the state of reading in Nigeria today is that we have a poor reading culture. Yet up to the early 70s’ school children had a healthy respect for reading because there was supportive environment for such activities through the school system, township/mobile libraries, British Council and United States Information Service (USIS) libraries, etc. To rekindle this interest would require not only the provision of reading materials but also democratising access, quality in time and space, environment considerations and technical expertise by teachers and enthusiasts. Above all, any intervention must be unobtrusive, yet must captivate the children especially given the ICT revolution which revolves round audio-visuals. One avenue for achieving this is the neighbourhood reading club. In this paper we present a report of a volunteer reading club situated within the University of Calabar for children of the neighbourhood. Insights into reading interests, impact of the club on the children’s emotional, educational and psychological development are explored with very surprising results and outcomes. Keywords: Neighbourhood reading clubs, reading culture, mobile libraries, reading materials democratizing access, volunteer reading club, reading interest, educational and psychological development

Optimizing Students’ Performance in English through Quality Teacher Education

Research has established significant connection between quality teacher education and student achievement. This cannot but be a concept in considering the performance of students in English language, a skill-based school subject. This paper examines the course content for language education for trainee teachers in the University of Calabar. This study appraises and validates the adequacy of the curriculum content to meet the language needs of the trainees with regard to transferring their learning to meeting the curriculum demands of secondary school English language learner. Suggestions towards optimizing quality teacher and professional education with the aim of improving performance in English language are proffered. Keywords: Student’s performance, English language, quality teacher education, curriculum content, trainee teachers

A weighted reduced basis method for parabolic PDEs with random data

This work considers a weighted POD-greedy method to estimate statistical outputs parabolic PDE problems with parametrized random data. The key idea of weighted reduced basis methods is to weight the parameter-dependent error estimate according to a probability measure in the set-up of the reduced space. The error of stochastic finite element solutions is usually measured in a root mean square sense regarding their dependence on the stochastic input parameters. An orthogonal projection of a snapshot set onto a corresponding POD basis defines an optimum reduced approximation in terms of a Monte Carlo discretization of the root mean square error. The errors of a weighted POD-greedy Galerkin solution are compared against an orthogonal projection of the underlying snapshots onto a POD basis for a numerical example involving thermal conduction. In particular, it is assessed whether a weighted POD-greedy solutions is able to come significantly closer to the optimum than a non-weighted equivalent. Additionally, the performance of a weighted POD-greedy Galerkin solution is considered with respect to the mean absolute error of an adjoint-corrected functional of the reduced solution.Comment: 15 pages, 4 figure

Letter processing and font information during reading: beyond distinctiveness, where vision meets design

Letter identification is a critical front end of the reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading

Piezoresistive microcantilever optimization for uncooled infrared detection technology

Uncooled infrared sensors are significant in a number of scientific and technological applications. A new approach to uncooled infrared detectors has been developed using piezoresistive microcantilevers coated with thermal energy absorbing materials. Infrared radiation absorbed by the microcantilever detector can be sensitively detected as changes in electrical resistance as function of microcantilever bending. The dynamic range of these devices is extremely large due to measurable resistance change obtained with only nanometer level cantilever displacement. Optimization of geometrical properties for selected commercially available cantilevers is presented. We also present results obtained from a modeling analysis of the thermal properties of several different microcantilever detector architectures